Giant frontoethmoid mucocele with intracranial extension: case report. (Original Article).

Abstract

We report the case of a 31-year-old woman who came to us with a giant frontoethmoid mass that had extended into the intracranial region and invaded the left orbit. We removed the lesion in its entirety via a combined intranasal and transcranial approach. We discuss the advantages and disadvantages of different surgical approaches, and we explain why we recommend a combined approach for the type of giant lesion that we encountered.

Introduction

Mucoceles are slowly growing but expansive lesions that usually originate in the frontal sinuses. (1) They occur as a result of an occlusion of the ostia of the paranasal sinuses by benign neoplasms (e.g., osteomas and fibrous dysplasias), by malignant or metastatic tumors, and by an intrasinusal accumulation of excreted substances secondary to infection, allergy, or trauma. (1) Men and women are affected equally, and these lesions are most frequently encountered during the third and fourth decades of life. (1) The incidence of skull base destruction caused by mucoceles is reported to be 10 to 20%. (2)

Surgical treatments include endoscopic sinus surgery and a craniofacial approach with or without sinus obliteration. (3,4) Mucocele invasion of the orbit and anterior cranial fossa requires an aggressive approach to eradicating the lesion. In this article, we report a case of a giant frontoethmoid mucocele that extended into the intracranial region and invaded the left orbit.

Case report

A 31-year-old woman came to our institution with a complaint of headache and a slowly progressive swelling of the left orbit and upper palpebra of 1 year's duration. Her history included several surgical interventions during a 9-year period for sinonasal polyposis, chronic sinusitis, and left frontal osteoma.

On physical examination, her left eye was proptotic and there was mild tenderness over the left frontal bone. Otherwise, findings on neurologic and ophthalmologic examinations were within normal limits. Magnetic resonance imaging (MRI) identified a 9 X 8 X 7-cm extra-axial lesion in the anterior cranial fossa that had eroded the frontal bone and the superior orbital wall on the left, extended into the left orbit and the right ethmoid cells, and compressed the frontal lobe (figure 1). The mass was heterogeneous on both T1- and T2-weighted MRI, hypointense on T1-weighted MRI, and hyperintense on T2-weighted MRI.

The patient underwent surgical removal of the lesion. A bony flap was obtained via a bifrontal craniotomy. Intraoperatively, we observed that the left orbit had been invaded and the posterior wail of the frontal sinus had been eroded, but the dura mater was intact. We completely excised the soft, yellow-gray mass over the dura mater and the left orbit via a combined intranasal and transcranial approach. We then made an osteoplastic flap closure and terminated the operation after nasal packing. The diagnosis was confirmed histopathologically.

The patient experienced no complication during recovery, and she was discharged 5 days postoperatively. At the 1-month follow-up, MRI detected no sign of recurrence (figure 2). At the 3-month follow-up, the proptosis of the left eye and the headaches had disappeared.

Discussion

Rollet first used the term mucocele in 1896. (5) Mucoceles are believed to develop secondary to the obstruction of the sinus ostium. The primary causes of such obstructions are sinusitis, allergy, trauma, surgery, and anatomic variations. Moreover, some authors have reported that tumors (including osteomas) can also obstruct the ostia of the sinuses. (1,6) We believe that the cause of the obstruction in our patient was her previous surgical interventions to treat sinonasal polyposis and left frontal osteoma.

Deformity and erosion of the sinus walls are caused in part by the mass effect of the lesion and by the presence of cytokines such as interleukin 1 (IL-i) and IL-6. (7,8) The lesion can extend into intracranial and orbital structures and lead to symptoms. The main signs and symptoms of orbital involvement are pain, proptosis, diplopia, exophthalmos, and loss of vision.9'10 The erosion of the posterior wall of the frontal sinus can lead to meningitis, meningoencephalitis, or cerebrospinal fistula. (11,12)

The diagnosis of mucocele is based on the history, physical examination, and radiologic findings. Computed tomography (CT) and MRI are effective in detecting the lesion and in demonstrating any intracranial extension. Mucoceles can be hyperdense (13) or hypodense (14) on CT, but brain and mucocele densities are usually equal. On Tiweighted MRI, the lesion can be either homogeneous or heterogeneous, and different signal patterns--such as hyper-, hypo-, and isointensity--can be seen. (15,16)

Several treatment options are available, and the choice depends on the degree of extension. Some authors believe that an intranasal approach is the first choice, even in patients with intracranial extension. (2) They argue that this approach is less invasive and they emphasize the possibility that the lesion can be diagnosed and completely removed without the need for craniotomy. On the other hand, Delfini et al prefer a transcranial approach for anterior mucoceles with intracranial extension to ensure complete removal and to prevent recurrence. (17) In our opinion, an intranasal approach can be used when the lesion is confined to the paranasal sinuses. However, if intracranial extension is confirmed, we prefer a combined intranasal and transcranial approach. In this way, the surgeon can achieve complete removal of the mucocele with wide exposure and a good cosmetic result. In addition, possible relapses are avoided.

Because the primary goals of surgery are to eradicate the mass with minimal morbidity and to prevent recurrence, several factors must be considered before deciding on a surgical approach. The exposition of the mass must be wide, the cosmetic outcome must be satisfactory, and the reconstruction of the region must be completed in one stage. During preoperative evaluation, either CT or MRI is essential to assess the presence or absence of extension and, if present, the nature of the extension. Because the orbit is the most frequently affected region, early drainage must be performed to avoid possible damage to the orbit. In patients with excessive intracranial extension in whom drainage is not possible, the lesion must be removed via a craniofacial approach. Cooperation among the otorhinolaryngology, neurology, and neurosurgery departments is critical in the preoperative assessment.

References

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From the Department of Otorhinolaryngology--Head and Neck Surgery (Dr. Cansiz, Dr. Yener, and Dr. Guvenc) and the Department of Neurosurgery (Dr. Canbaz), Cerrahpasa School of Medicine, Istanbul University, Turkey.

Reprint requests: Harun Cansiz, MD, Nato Yolu, Caprazli Alt Sok. 12/7 Cengelkoy/Uskudar, Istanbul, Turkey. Phone: [phone]; fax: [phone]; e-mail: [e-mail]